build: remove workarounds for gcc <= 4.4

Now that V8 requires a compiler with decent C++11 support, there is no
reason to keep supporting old versions of gcc.  Remove workarounds for
bugs in gcc 4.4 and older.

This coincidentally makes it easier to build with clang 3.3 + address
sanitizer because clang no longer chokes on the `-fno-tree-vrp` switch.

PR-URL: https://github.com/node-forward/node/pull/24


Reviewed-By: Fedor Indutny <fedor@indutny.com>